Thermal control for additive manufacturing

ABSTRACT

An additive manufacturing system for building a product includes a base plate for mounting the product thereon, and at least one heating element shaped to at least partially conform to the product and configured to apply heat to at least a portion of the product as the product is additively manufactured to reduce thermal gradients in the product.

BACKGROUND 1. Field

The present disclosure relates to additive manufacturing, morespecifically to thermal control for additive manufacturing.

2. Description of Related Art

All welding and joining processes create non-uniform residual stressdistributions as a result of the intense heat input. Residual stressesdue to thermal expansion and contraction of the solidified material cancause distortion of an additively manufactured part. Distortion canoccur during the additive manufacturing process and/or during the heattreatment cycles after building. The residual stress in the part canrelax during heat treatment causing significant distortion to occur.

As such, thermal management is required to prevent thermalcontraction/shrinkage from occurring during the process. Thermalcontraction can lead to layer misregistration where the layer beingfused does not dimensionally correlate to the previous layer.Traditional additive manufacturing processes and systems do not controlsuch non-uniform residual stresses.

Such conventional methods and systems have generally been consideredsatisfactory for their intended purpose. However, there is still a needin the art for improved thermal control for additive manufacturing. Thepresent disclosure provides a solution for this need.

SUMMARY

An additive manufacturing system for building a product includes a baseplate for mounting the product upon, and at least one heating elementshaped to at least partially conform to the product and configured toapply heat to at least a portion of the product as the product isadditively manufactured to reduce thermal gradients in the product(e.g., due to non-uniform heating/cooling of the product duringsintering).

The heating element can be conformal to an outer shape of the product.The heating element can include an electric coil or any other suitableheating element.

In certain embodiments, the base plate can be configured to be heated.The system can include a thermal imaging device (e.g., an IR camera)positioned to view the product within the heating element for thermalmonitoring of the product as it is additively manufactured.

The system can include a control unit operatively connected to thethermal imaging device and the heating element to control the heatingelement as a function of feedback from the thermal imaging device toprevent non-uniform heating of the product. In certain embodiments, thesystem can include an energy applicator positioned to apply energywithin the heating element for layer-wise powder fusion.

A method for additively manufacturing a product includes additivelymanufacturing a product on a base plate and within a heating element,and applying heat to a portion of the product during additivemanufacturing to reduce thermal gradients in the product, whereinheating the product occurs within a heating element configured to atleast partially conform to the product. In certain embodiments, additivemanufacturing the product can include depositing powder within theheating element.

The method can further include applying energy from an energy applicatorto the powder within the heating element to sinter the powder within theheating element. In certain embodiments, the method can includecontrolling the heating element as a function of feedback from a thermalimaging device to prevent non-uniform heating of the product. The methodcan include heating the base plate.

These and other features of the systems and methods of the subjectdisclosure will become more readily apparent to those skilled in the artfrom the following detailed description taken in conjunction with thedrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

So that those skilled in the art to which the subject disclosureappertains will readily understand how to make and use the devices andmethods of the subject disclosure without undue experimentation,embodiments thereof will be described in detail herein below withreference to certain figures, wherein:

FIG. 1 is a perspective exploded view of an embodiment of a system inaccordance with this disclosure.

DETAILED DESCRIPTION

Reference will now be made to the drawings wherein like referencenumerals identify similar structural features or aspects of the subjectdisclosure. For purposes of explanation and illustration, and notlimitation, an illustrative view of an embodiment of a system inaccordance with the disclosure is shown in FIG. 1 and is designatedgenerally by reference character 100. The systems and methods describedherein can be used to reduce defects due to non-uniform heating/coolingduring additive manufacturing.

Referring to FIG. 1, an additive manufacturing system 100 for building aproduct 102 includes a base plate 101 for mounting the product 102 uponand at least one heating element 103 shaped to at least partiallyconform to the product 102 (e.g., completely around, adjacent one ormore lateral sides or portions thereof) and configured to apply heat toat least a portion of the product 102 as the product 102 is additivelymanufactured to reduce thermal gradients within the product 102. Anysuitable number of heating elements 103 can be utilized. It should beunderstood that the heating element 103 may not actually increasetemperatures within the product 102, but instead slow a rate of coolingof the product 102. In so doing, the heating element 103 may reducethermal gradients in the product 102 (e.g., due to non-uniformheating/cooling of the product 102 during the additive manufacturingprocess)

In certain embodiments, the heating element 103 can be conformal to theouter shape of the product 102 such that it surrounds the product 102,for example. The heating element can include an electric coil (e.g., aninduction coil) or any other suitable heating element that extends alonga build axis.

In certain embodiments, the base plate 101 can be configured to beheated (e.g., via one or more heating elements disposed within the baseplate 101). For example, the base plate 101 can include a resistiveheating arrangement with heating elements attached to the bottom of thebase plate 101 or embedded within the base plate 101 (e.g., usingadditive manufacturing techniques). Certain embodiments of the baseplate 101 can have integral heat pipes that define heating channels fora heating fluid to be pumped through to stabilize temperature. Incertain embodiments, a part may be used as the base for deposition tocreate features or shapes instead of manufacturing the entire partthrough additive manufacturing methods.

The system 100 can include a thermal imaging device 105 (e.g., an IRcamera) positioned to view within the heating element 103 for thermalmonitoring of the product 102 as it is additively manufactured. Incertain embodiments, the system 100 can include an energy applicator 109(e.g., a laser) positioned to apply energy within the heating element103 for layer-wise powder fusion. While embodiments can be used withdirected energy deposition or blown powder deposition processes (e.g.,for metals), it is contemplated that molten material deposition (e.g.,for thermoplastics) can also be utilized within the heating element.

As shown, the system 100 can include a control unit 107 operativelyconnected to the thermal imaging device 105, the heating element 103,the base plate 101, and/or the energy applicator 109 to control theheating element 103 and/or the energy applicator 109 and/or the baseplate 101 as a function of feedback from the thermal imaging device 105to prevent non-uniform heating and/or reduce thermal gradients withinthe product 102. For example, if a local hot spot is detected, thecontrol unit 107 can cause the heating element 103 to apply more heat tothe product 102 being built.

In accordance with at least one aspect of this disclosure, a method foradditively manufacturing a product 102 includes additively manufacturinga product 102 on a base plate 101 and within a heating element 103. Themethod also includes applying heat to the product 102 during additivemanufacturing to prevent non-uniform heating of the product 102.

In certain embodiments, additive manufacturing the product 102 caninclude depositing powder within the heating element 103. For example,powder can be dropped or sprayed (e.g., via a cold spray process) in anysuitable manner. The heating element 103 can be progressively submergedin powder, or powder can be deposited only within the confines of theheating element 103 such as on the product 102 only, for example. It iscontemplated that any other suitable method to place powder within theheating element 103 is contemplated herein.

The method can further include applying energy from an energy applicator109 to the powder within the heating element 103 to sinter the powderwithin the heating element 103. In certain embodiments, the method caninclude controlling the heating element 103 as a function of feedbackfrom a thermal imaging device 105 to prevent non-uniform heating of theproduct 102. The method can also include heating the base plate 101.

As described above, embodiments include a heating element that can benearly conformal to the finished part. The heating element 103 extendsin the z-axis (i.e., the axis in which the part is being built).Multiple heating elements 103 could be used as needed to optimize thethermal management throughout the production of a part. Also, the powersettings for the heating element 103 could be varied as needed usingpre-established parameters to create a smaller or larger inducedmagnetic field. The base plate 101 can also be utilized as the startingsurface for manufacturing of the part. To maintain a uniformtemperature, the base plate 101 can be heated.

Embodiments as described above allow for improved distortion control,consistent registration between layers, minimized temperaturedifferences within part, reduced risk of solidification cracking orissues with solidification (e.g., during a laser fusion additivemanufacturing process).

The methods and systems of the present disclosure, as described aboveand shown in the drawings, provide for additive manufacturing systemswith superior properties as described above. While the apparatus andmethods of the subject disclosure have been shown and described withreference to embodiments, those skilled in the art will readilyappreciate that changes and/or modifications may be made thereto withoutdeparting from the spirit and scope of the subject disclosure.

What is claimed is:
 1. An additive manufacturing system for building aproduct, comprising: a base plate for mounting the product upon; and atleast one heating element shaped to at least partially conform to theproduct and configured to apply heat to at least a portion of theproduct as the product is additively manufactured to reduce thermalgradients in the product.
 2. The system of claim 1, wherein the baseplate is configured to be heated.
 3. The system of claim 1, wherein theheating element includes an electric coil.
 4. The system of claim 1,wherein the heating element is conformal to an outer shape of theproduct.
 5. The system of claim 1, further comprising a thermal imagingdevice positioned to view the product within the heating element forthermal monitoring of the product as it is additively manufactured. 6.The system of claim 5, further comprising a control unit operativelyconnected to the thermal imaging device and the heating element tocontrol the heating element as a function of feedback from the thermalimaging device to reduce thermal gradients in the product.
 7. The systemof claim 1, further comprising an energy applicator positioned to applyenergy within the heating element for layer-wise powder fusion.
 8. Amethod for additively manufacturing a product, comprising: additivelymanufacturing a product on a base plate and within a heating element;and applying heat to a portion of the product during additivemanufacturing to reduce thermal gradients in the product, whereinheating the product occurs within a heating element configured to atleast partially conform to the product.
 9. The method of claim 8,wherein additive manufacturing the product includes depositing powderwithin the heating element.
 10. The method of claim 9, furthercomprising applying energy from an energy applicator to the powderwithin the heating element to sinter the powder within the heatingelement.
 11. The method of claim 8, further comprising controlling theheating element as a function of feedback from a thermal imaging deviceto reduce thermal gradients in the product.
 12. The method of claim 8,further comprising heating the base plate that the product is mountedon.